The skin is a complex multi-layered organ. The outer layer of the skin is the epidermis having a thickness of between 0.05 mm (eyelids) and 1.5 mm (palms and soles) made up of keratinocytes, melanocytes, Langerhans cells, and Merkel cells in five layers. Under the epidermis is the dermis having a thickness of 0.3 mm (eyelids) to 3 mm (back), primarily comprising collagen, elastic fibers and extrafibrillar matrix in two layers, the upper papillary layer and the lower reticular layer. Under the dermis is the hypodermis housing large blood vessels and nerves primarily comprising fibroblasts, adipose cells, and macrophages.
It is often desired to remove unsightly blemishes on the skin of an animal. In some instances there is a medical reason for removing such blemishes, for example to remove warts or precancerous growths. That said, often it is desired to remove or reduce the extent of a skin blemish for exclusively cosmetic reasons.
In the art, it is known to remove skin blemishes by damaging the skin or the blemish and the letting the skin heal. The thus-rejuvenated skin is often devoid of the blemish or the extent of the blemish is somewhat reduced.
Methods for damaging the skin to remove blemishes include peeling with abrasives (e.g., ground cherry or olive pits), peeling with chemical solutions (e.g., including phenol, trichloroacetic acid or alpha hydroxy acids) or ablation by heating (e.g., with electromagnetic radiation such as from a laser) to remove blemishes such as acne scars, wrinkles, fine lines age spots , uneven skin tone, pigmentation, large pores and the like.
It has been found that in some instances improved results are achieved when, instead of damaging a large contiguous area of skin, many small areas of the skin are damaged and allowed to heal, a technique known as fractional technology. It is believed that the body can more easily heal a small damaged area surrounded by healthy tissue then a large damaged area. Further, as in fractional technology the area of the damaged skin is relatively small, it becomes possible to damage the area of skin more deeply, leading to more effective treatments of blemishes as well as a greater skin-rejuvenating effect, attributed to more effective stimulation of new collagen growth. In some instances, a fractional technology treatment must be repeated a number of times in the same area of skin to achieve maximal desired effect.
One typical implementation of fractional technology is fractional laser therapy (e.g., using the Pixel Perfect™ by Alma Lasers Ltd., Caesaria, Israel) where a laser beam is directed at an area of skin to produce a large number of small perforations (e.g., 49 perforation/cm2, each perforation about 0.2 mm diameter). Such treatment has been shown to be effective in stimulating new collagen and blood vessel development, improving skin texture and tone as well as removing fine lines, wrinkles, acne scars and uneven pigmentation. Similar devices have been described, for example, in PCT Patent Publication WO 2008/083305.
One typical implementation of fractional technology is based on mechanical damage to the skin, for example using the Dermaroller(r) (available from Dermaroller s.a.r.1, Friesenheim, France), a needle-studded roller that, when rolled over a skin surface, physically pierces the skin with about 250 punctures/cm2 to a depth of 0.3 mm to 1.5 mm. Such treatment is alleged to stimulate new collagen and blood vessel development, to remove wrinkles, reduce hyper pigmentation, striae, acne scars and bum scars.
Although known methods of dermatological treatment are often effective, there is an ongoing need to improve such treatments. For some blemishes such as deep pigmentation blemishes, known dermatological treatment methods are not insufficiently effective.